atomicity.h: New file.

2003-04-29 Joel Sherrill  <joel.sherrill@OARcorp.com>
	   Loren J. Rittle <ljrittle@acm.org>
	   Martin v. Loewis  <martin@v.loewis.de>

	* config/cpu/i386/atomicity.h: New file.

Co-Authored-By: Loren J. Rittle <ljrittle@acm.org>
Co-Authored-By: Martin v. Loewis <martin@v.loewis.de>

From-SVN: r66261

libstdc++-v3/ChangeLog

+2003-04-29 Joel Sherrill  <joel.sherrill@OARcorp.com>
+	   Loren J. Rittle <ljrittle@acm.org>
+	   Martin v. Loewis  <martin@v.loewis.de>
+
+	* config/cpu/i386/atomicity.h: New file.
+
 2003-04-29  Paolo Carlini  <pcarlini@unitus.it>
 
 	* include/bits/fstream.tcc (open): Change to single return.

libstdc++-v3/config/cpu/i386/atomicity.h

+// Low-level functions for atomic operations: x86, x >= 3 version  -*- C++ -*-
+
+// Copyright (C) 2003 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 2, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING.  If not, write to the Free
+// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+// USA.
+
+// As a special exception, you may use this file as part of a free software
+// library without restriction.  Specifically, if other files instantiate
+// templates or use macros or inline functions from this file, or you compile
+// this file and link it with other files to produce an executable, this
+// file does not by itself cause the resulting executable to be covered by
+// the GNU General Public License.  This exception does not however
+// invalidate any other reasons why the executable file might be covered by
+// the GNU General Public License.
+
+#ifndef _BITS_ATOMICITY_H
+#define _BITS_ATOMICITY_H	1
+
+typedef int _Atomic_word;
+
+template <int __inst>
+struct __Atomicity_lock
+{
+  static volatile _Atomic_word _S_atomicity_lock;
+};
+
+template <int __inst>
+volatile _Atomic_word __Atomicity_lock<__inst>::_S_atomicity_lock = 0;
+
+template volatile _Atomic_word __Atomicity_lock<0>::_S_atomicity_lock;
+
+static inline _Atomic_word 
+__attribute__ ((__unused__))
+__exchange_and_add (volatile _Atomic_word *__mem, int __val)
+{
+  register _Atomic_word __result, __tmp = 1;
+
+  /* obtain the atomic exchange/add spin lock */
+  do {
+    __asm__ __volatile__ ("xchgl %0,%1"
+			  : "+m" (__Atomicity_lock<0>::_S_atomicity_lock),
+			    "+r" (__tmp));
+  } while (__tmp);
+
+  __result = *__mem;
+  *__mem += __val;
+
+  /* release spin lock */
+  __Atomicity_lock<0>::_S_atomicity_lock = 0;
+
+  return __result;
+}
+
+static inline void
+__attribute__ ((__unused__))
+__atomic_add (volatile _Atomic_word* __mem, int __val)
+{
+  __exchange_and_add (__mem, __val);
+}
+
+#endif /* atomicity.h */